This invention relates to a method for processing animated graphics to change or shift a displayed position of a graphic symbol having fixed sizes or dimensions.
In a prior art technique of this field, when it is desired to parallelly shift the displayed position of a graphic symbol FS consisting of about one hundred straight lines as shown in FIG.1 by five dots in an upper direction and five dots in a leftward direction, it is necessary to erase an old graphic symbol OF and display and process a new graphic symbol NF at a new display position of the cathode ray tube (CRT) display of graphic dot information described on a video RAM ( Random Access Memory ) as shown in FIG.2. In other words, it was necessary to interpret and excecute commands for erasing the respective lines for the old graphic symbol OF and for displaying the respective lines for the new graphic symbol NF.
FIG.3 is a block diagram showing a system in a prior art for processing animated graphics of the type described above, in which a graphic processing command unit 1 operates so as to read out information regarding the respective lines constituting the graphic symbol FS for the animation graphic, for example, coordinate values of the start and terminal points, kinds of the lines and the like, from a symbol line data registering unit 10, to form a command LE in case of commanding the description of the lines or erasing the symbol, and to transfer the command LE to a graphic processing control unit 2. The graphic processing control unit 2 interprets the line description command LE or erase command LE prepared in and transferred from the graphic processing command unit 1 with respect to the respective lines, so as to thereby convert the coordinate on the screen of a CRT display unit 6 into an address of a video RAM 4 which is a memory element for storing the display graphic and to perform a clipping processing for the designated area as occasion demands. The command LE subjected to these processings is converted into concrete dot information in a line describing unit 30 and the graphic dot information is stored at a corresponding position in the video RAM 4. In case of the command LE for erasing lines, the erasing command LE is convertedinto concrete dot information in a line erasing unit 31 in place of the line describing unit 30 and stored in the video RAM 4. The graphic information thus stored in the video RAM 4 is converted into a graphic display signal suitable for the CRT display unit 6 as the graphic display unit in a video signal forming unit 5 and then transferred into the CRT display unit 6 so as to thereby display the graphic symbol on the screen.
As described hereinabove, with the conventional animated graphic processing method, two steps were required for erasing the old graphic symbol and for displaying the new graphic symbol on a new display position, so that the delay for the graphic display was noticeable and it was impossible to realize the smooth shift or display of the graphic symbol.